Connect with us

UIC option in SPICE?

Discussion in 'Electronic Basics' started by billcalley, Jun 23, 2005.

Scroll to continue with content
  1. billcalley

    billcalley Guest

    I have read all I could find about the Use Initial Conditions (UIC)
    option in SPICE, but I still don't fully understand it. The reason I
    am confused is this: When I run a DC transient analysis with UIC
    enabled on a simple RLC tank circuit (with all passives having an IC of
    '0'), shouldn't these results be the same as a DC transient
    simulation with *no* UIC, since they should both have a initial
    starting condition of 0V/0A? Yet with the simulation with no UIC
    enabled, the circuit reaches steady state instantly; while with the UIC
    option enabled it takes a finite time to reach its voltage level, then
    over/undershoots a few time (rings) -- as it should. What am I missing
    here?

    Thank You,

    -Bill
     
  2. If UIC is not specified then SPICE does not assume zero initial conditions.
    By default SPICE will solve for the DC operating point of the circuit before
    performing a transient analysis, and use that for the initial conditions.

    The originating message was also posted to sci.electronics.cad but was not
    cross-posted, so I have cross-posted now.

    Jonathan
     
  3. billcalley

    billcalley Guest

    Thanks very much for the clear answer Jonathan! Very much appreciated.

    Best Regards,

    -Bill
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-